The aim of this study is to improve the description of a construct of affective dysregulation, which appears to indicate an increased risk for serious mood, anxiety and behavioral disorders. Recent evidence exploring the comorbidity between oppositional defiant disorder (ODD) and depression has found that a subset of ODD symptoms (being angry, touchy, spiteful or vindictive, and problems with temper) serves to explain the comorbidity between the conditions. These items have also been shown to predict an increased severity of subsequent anxiety and depression. As such, they appear to describe a dimension of affective dysregulation. The present study will employ advanced statistical techniques to explore this construct and build upon initial evidence in several significant ways. First, it will determin if additional indicators, outside of the set of symptoms of ODD, may be used to improve the description of the construct. Secondly, it will determine if distinct groups of youth are identifie using this construct, and whether they are at increased risk for poor outcomes. The study will determine whether groups identified by these items differ from those identified by either existing or newly proposed diagnostic categorizations. Further, this study will provide an estimate of the heritability of affective dysregulation using a large, well-described twin data set. Finally, the study aims to establish the degree to which affective dysregulation increases the risk for mood, anxiety and behavioral disorders, as well as for suicidal behaviors and violence. This study will use data from four large, well- described longitudinal community data sets to conduct coordinated secondary data analyses. These analyses will include latent variable techniques to explore content validity of potential indicators of affective dysregulation, latent class and laten transition analyses to estimate the identification of distinct groups of children using this construct, and generalized estimating equation techniques to describe the developmental risk for severe psychopathology. PUBLIC HEALTH RELEVANCE: This research is relevant to public health in that it is designed to generate new information to improve the ability to predict which children and adolescents are at risk for severe psychopathology and for outcomes of suicide and violence. This information will significantly enhance clinical practice in prevention efforts, improved treatment strategies and risk management, and the resolution of questions regarding developmental and diagnostic models.